Grinding machine



Feb. 27, 1934. H Loo r l,948,899

GRINDING MAGHINE Filed 'June 1931 2 Sheets-Sheet 1 ame/nie@ Harold.LBlood 7 %1, waw

Feb. 27, 1934. 'a on 1,948,899

GRINDING MACHINE Filed June 1931 2 streets-sheet 2 sme/4 01.

Hmm LBooa Patented Fel.` 27, 1 934 UNITED STATES PATENT OFFICE TheBleals Machine (Company, Worchester,

Mase, a carparation aii Massaclusetts Applicaticn .t'ime lili, 1931..

The invention relates to grinding machines and particularly to internalgrinding machines which are used for grindng the internal cylindrical orconical surfaces of sleeves, gears. bush- 5 ings and like articles. v

In grinding with a machine of the type disclosed in Patent No. 1,682,672issued August 28, 1928 to Guild or of the type disclosed in Patent No.1,73l,719 issued October 15, 1929 to Kempton and Gallimore, the grindingwheel enters the work and is reciprocated therein to produce a relativetraversing movement between the wheel and the work until the workpieceis ground to the desired finished size when the wheel is automaticallyremoved from contact with the workpiece and is run out automatically toits rest position. In such machines, the wheel is fed transverselyagainst the surface being ground, in order that the wheel will cutprogressively deeper and deeper into the workpiece, by a relativecrossfeed movement of said grinding wheel and work, which movement isimparted`in a step-by-step relation by automatic mechanism responsive tothe relative traversing movement, said crossfeed mechanism beingactuated during the entire operation of the machine. The progressivecross-feed which urges the wheel against the surface being groundcarries the wheel with greater 'and greater pressure against theworkpiece, the surface of the workpiece being removed to a less depththan the corresponding movement of the wheelhead toward the workpiece.This pressure causes the spindle carrying the wheel to be Sprungsomewhat and this spindle spring together with the excessive pressurebuilt up between the wheel and work produces an uneven grinding actionwith the result that the finished surface is rough and often irregular.During the normal reciprocatory movement of the wheel 40 over thesurface being ground the pressure established by the cross-feed movementis distributed over the entire width of the grinding wheel. However,when the wheel is being separated from the work at the completion of-the grinding, the pressure area is diminishe'd, and

the pressure for each unit of area is thereby inthe objectionablebelbmouthing still occurs when the wheel is separated from 'the work.

Ideal 'grinding conditions prevail when there is practically no pressureexerted by the wheel against the work, and the object of the presentinvention is to provide a grinding machine which will relieve thepressure built up by the crossfeed movement of the grinding wheel priorto withdrawal of the wheel from the work and which incorporates theadvantages of the grindlili' ing machines disclosed in the above citedpatents. According to the present inventionothe cross-feed movement ofthe grinding wheel is discontinued beforethe wheel is withdrawn fronpthework so that the wheel in completing the grinding is I@ allowed totraverse the surface being ground with no cross-feed movement beingimparted thereto, the small amount of pressure or spindle spring whichwas built up during the operation of the cross-feed movement causing thewheel to grind N under gradually diminished pressure until the spring inthe spindle is no longer efiectve or, in other words, until the grindingwheel sparks out., after which the wheel and work are separated;

This invention is similar to the invention d's- 00 closed in thecopending application of Heald, Serial No. 542240, filed June 5, 1931,in which the mechanis'n by which the cross-feed is dis-' continued priorto withdrawal of the grinding wheelfrom the workpiece and ismechanically u actuated. The present invention provides electricallycontrolled mechanism bywhich to procure cessation *of the cross-feedprior to withdrawal of the wheel from the workpiece. Other and furtherobjects and advantages of the invention will appear from the followingdetailed description thereof, reference being had in` this connection tothe accompanying drawinga. wherein- Fig. 1 is a. front elevation of aninternal grinding machine embodying the invention.

i Fig. 2 is an enlarged front elevation of the cross-feed mechanismparts being broken away to show the construction thereof.

Fig. 3 is awiring-diagram. Fig. 4 is an alternative wiring diagram foruse with a modified grinding machine;

Like reference characters refer to like parte throughout the drawings.

Referring first to Fig. 1, an internal 'grinding machine is shown havingthe reciprocatory table or' carriage 1 ordinarily provided in internalgrindng machines. In such a. machine, either the grinding wheel or thework to be ground maybe carried on the table l. the recip- 110 2, andany suitable means, which need not herein be described, is provided torotate said spindle 6 and wheel 5. The workpiece, which is held within asuitable chuck on the inner end of the workhead 3, is also rotated, butdesirably at a slower speed.

The reciprocation of the table 1 to cause the rotating grinding wheel 5to make the required interier ,traverse of the rotating workpiece may beimparted in any well-known manner, as for instance by the use of thefluid pressure controllingand reversing mecham'sm described in Unitedstates Letters Patent No. 1,582,468, granted 'April 27, 1926 to Healdand Guild. such mechanism is now well-known in grinding machines andrequires no detailed description; it is suflicient to note for presentpurposes, that the driving means employed for the reciprocation of thetable 1, be it hydraulic drive, or gear drive, or any other type,procures the reversal of said table at each end of the latter's normalworking stroke by the use of spaced adjustable dogs 7 and 8, carried bythe table l-and adapted alternately to engage and to move a reversingmember 9; the latter, during the grinding operation, when the wheel 5 ismoving back and forth within the workpiece 6, is situated between thetwo dogs 7 and 8 in a position to be struck alternately by said dogs,and by its consequent movement, first in one way and then the other,effects the reversals in the 'travel of the table 1.

The above described mechanism is all old and well known in the art andof itself forms no part of the present invention. The latter involvesthe attainment, in connection with such or similar grinding machineinstrumentalities, of the novel and useful objects and resultshereinbefore set forth. In the present machine, a crossfeed between workand grinding wheel is obtained by moving the wheelhead 2 transversely'of the reciprocatory table 1 but, obviously, the

invention is not limited in this respect, since the cross-feedmechanism, as hereinafter described, might as readly be applied to thetransverse movement of the workhead 3.

The wheel head 2 of the machine is mounted on a cross-slide, not shown,which is adapted to have an in and out movement on the reciprocatorytable 1; movement of the slide is obtained by` rotation of a threadedshaft 11 held against longitudinal movement in the table 1, the shaftengaging an internally threaded member Secured to the cross-slide.Rotation of the threaded shaft 11 to p'rocure the in and cut movement ofthe cross-slide is effected in the following manner:-

As the table 1 is reciprocated over the work, a cam 12 which isadjustably mounted on a horizontal extension 13 of the workhead 3engages a roller 14, Fig. 2, mounted on an arm 15 which is journalled ona stud 16 on the table 1, thereby rocking said arm upwardly. A pawl 17which is pivotally mounted on the outer end of the arm 15 engages ateach rocking movement of the arm with one of the teeth on a ratchetwheel 18, im-

'at each reciprocation of the table. `workpiece reaches a, predeterminedsize prior to parting a step-by-step rotary movement thereto. Theratchet wheel 18 (Fig. 2) is operatively secured to the threaded shaft11 in any desired manner, for example, in the manner shown 'in the abovecitedpatent to Guild, and the step-by-step rotation of the table 1imparts, through the operative connection, a, step-by-step cross-feedmovement to the cross-slide. A hand wheel 19 is rigidly Secured to theratchet wheel 18, and provides a means by which the cross-slide may berepositioned after the completion of a grinding operation to place thegrinding wheel in a position to enter a new workpiece.

After a predetermined period' of grinding the grinding wheel iswithdrawn from operative relation to the workpiece to permit a dressingoperation to be performed on the wheel *to-provide a smooth grindingsurface and, after being again placed in operative relation to the work,is withdrawn after the workpiece is completely ground. The separation of-the wheel and the work is obtained by gauge devices of the typedisclosed' in Patent No. 1,534,302, issued April 21, 1925 to Conradsonet al. The particular gauge Construction is not, of itself, theinvention in this application. It is sufficient, for the purposes of thepresent invention, to note that a roughing gauge and a finish gauge aremounted in the workhead and are pressed against the end of the workpieceWhen the 105 the final grinding operation, the roughing gauge enters theinternal surface of the workpiece. The longitudinal movement imparted tothe gauge as it enters the workpiece, makes an electrical contactthereby closing an electrical circuit, which circuit is used, in thepresent application, to procure separation of the wheel and work for thedressing or truing operation on the wheel. The

separation of wheel and work is accomplished in the following manner:--

Referring to the wiring diagram of Fig. 3, the contact points 20 and 21represent the gauge contacts which are connected when the rough gaugeenters the bore of the workpiece to cause the table 'to be withdrawnfrom normal reciprocatory position for the dressing operation on thewheel. The contact 20 is connected to a ground 22 by a lead 23, andcontact 21 is connected by a lead 24 to one side of an electromagnet 25,the other terminal of the electromagnet being' conected by a lead 26 toone plate 27 of a switch 28, the latter being mounted on the front ofthe machine. A moving blade 30 of the switch is in contact with theplate 27, saidblade 30 being connected by a lead 31 to one terminal of agenerator 32, the other terminal of the latter being grounded at 33. Amanually operated switch 34 is provided in the ground connection torender the electrical circuits inoperative, said switch being normallyclosed. Accordingly, when the circuit is closed by engagement of thecontacts 20 and 21, switch 34 being in closed position, theelectromagnet 25 is energized causing attraction of an armature member35 and the consequent elevation of its attached lever arm 36, theseparts being pivoted at 37 on the front of the machine. such movement ofthe lever arm 36, responslve to the engagement of gauge con-` tacts 20and 21 is made use of automatically to interrupt the grinding operationon the workpiece 6 for the dressing and truing of the grinding wheel 5,in advance of the final and flnishing outs taken by 'said wheel to bringthe workpiece to the desired size. This involves the withdrawal of thegrinding wheel 5 from the workpiece, and I Qit the disposal in thetemporarily amplifled path of movement oi said wheel of a dressingdevice or diamond two Operations are eifected through the medium of thelever arm 36 in the manner fully described in the patent issued to Healdand Guild, No. 1,779,094, granted October 21, 1930, in which thedressing device 38 is moved into operative position through the mediumor fluid under pressure. It is sufiicient to note, tor purposes of thisapplication, that, as described in said Heald and Guild Patent No.1,779,094, the dresser point 38 is lowered into operative position bythe downward swinging movement of a carrying member 40. When the leverarm 36`is moved, a downward extension 41 thereof communicates saidmovement to a valve, not shown, thus making the pressure fluid active,through suitable connections, against a pisten, not shown, which isoperatively asscciated with the member thereby to Swing the dresserpoint 38 from the inoperative position that it normally occupies downinto its operative position in the path of grinding wheel 5.' Theinvention, of course, is not limited to the above described use ofpressure fluid for disposing the dresser 38 in operative position;obviously, any other type of dresser moving mechanism may be used.

As before stated, the other operation inaugurated by said engagement isthe automatic amplification of the reciprocatory path of table 1 toCarry the wheel 5 past the dresser 38. As shown in Fig. 1, the left handtable dog 8 which limits the right hand movement of table 1, is c'arriedby a block 42 which, instead of being Secured directly to the table 1 asis the case with the block 43 of dog 7, is mounted so as to be capableof sliding freely longitudinally of said table. Under normal conditions;when the table is making its usual working reciprocations to traversethe grinding wheel 5 back and forth within the workpiece, the block 42of dog 8 is held in definite spaced relation to a block 44, whichlatter, the

same as the block 43 of right hand dog 7, is a stationary block adaptedto maintain' its predstermined setting or adjustment longitudinally ofthe table 1.

The device employed to hold the slidable block 42 in spaced relation tothe fixed block 44 is here shown as a latch lever 45 pivoted on block 44and having its free end disposedby gravity in abutting relation to ashoulder on block 42, .thereby holding the block 42 at a predetermineddistance to the right of block 44. When the latch member 45 is lifted tofree its end from the shomder, the normal connection between the slidingblock 42 and the fixed block 44 is' broken. and when this occurs on theright hand movement of table 1, the dog 8 will bear without eflectagainst the member 9. Thus the right hand movement of the table 1 onthis particular stroke will be ex tended beyond the usual reciprocatoryworking path and the grinding wheel 5 will be carried out' of the holein the workpiece to a point just beyond that occupied by the dressingdevice, which latter, as already described, has been moved intooperative position as the amplifled right hand travel 'of table 1begins. This amplified right.

upon the solid hacking thus 'afiorded for the block 42 enables thedog 8to shii't the member 9. This procures reversal of the table 1 and theleft hand movemento' said table thus inaugurated lt aused i to restorethe parts automatically to'normal position in the manner disclosed inthe above identi 'fied patent to Guild, so that the dog 8 is again inthe operative position of Fig. 1.

said single amplified reciprocation of the table 1 for wheel dressingpurposes is, in the present invention, inaugurated automatically upon aprei again passing said diamond before resuming the normalreciprocatorytraverse of the workpiece 6. Thereupon, by any suitable means, such asthat shown and described in the aforesaid Patent No. 1,779,094 of Healdand Guild, the diamond 38 is rocked upwardly into the inoperativeposition that it normally occupies.

On this amplified right hand dressing stroke of the table 1, an arm 46,Fig. 3, pivoted at 47 on the block 44, and hanging by gravity in theposition shown in Fig. 3, strikes an'arm 48, Fig. 3, of movable switchmember, thereby rocking said switch member away from bar 27 to prevent arepetition of the dressing stroke.

The cross-feed movement is discontinued at this point in the grindngoperation to permit the pressure of the grinding wheel during the out.Cessation of the cross-feed movement is obtained during the amplifiedright hand dressing stroke of the table l, on which dressing stroke, asabove pointed out, the switch member 30 is rocked away from the'bar 27,thereby moving said member 30 into engagement with a plate 50 which isarranged to procure disengagement of the pawl 17 from the ratchet wheel18 in the following mannerz Referring to the wiring diagram of Fig. 3,the plate 50 is connected by a lead 51 to one terminal of anelectromagnet 52, the other terminal being connected to a ground 53 bylead 54. Since the moving blade 30 of the switch is connected to oneterminal oi the generator 32, engagement of the ablade 30 and plate 50energizes the electromagnet 52 causing attraction of anarmature member55. This movement of the armature` clisengages the ratchet and' pawl asfollows:

Referring now to Fig. 2, a depending arm 56 is pivoted on a stud 57 onthe table 1 and carries adjacent the lower portion thereof a cam 58which a is adapted upon swinging movement of the arm 56 to engage with adepending lug 60 on the pawl 17 to withdraw saidpawl from engagementwith the ratchet 18. The lower end of the arm 56 isconnected to one endof the armature 55 by a rod 61, the opposite end of the armature beingpivoted at 62 to a portion oi the table 1. Attraction of the armature 55the electromagnet 52 moves the cam 58 into engagement with the lug 60,thereby maintaining the pawl 17 out .of engagement with the ratchetwheel 18 until the electromagnet is deenergized; said magnet is'deenergized at the beginning o! a subsequent grind ing operation aswill be hereinatter pointed out.

gauge enters the workpiece.

After the .wheel dressing operation above de-` scribed, grinding isresumed upon the workpiece 6 and continued, without cross-feed movement,until a finish gauge of the type disclosed' in the above mentionedConradson et al. patent, and actuated in a similar manner, enters thework. The particular operation of this gauge s not of itself theinvention in this application, and it is sufiicient to note, as pointedout with reference to the roughing gauge, thatwhen the workpiece reachesthe exact desired size, this size being the size of a completedworkpiece, a finish gauge enters the internal surface of the work, thelongitudinal movement of the gauge as it enters the work making anelectrical contact, thereby closing a circuit which acts in the presentapplication to withdraw the wheel from the work and to cause the wh'eelto be carried to rest position. In the diagram of Fig, 3, the contactpoints 63 and 64 represent the contacts between which electricalconnection is made when the finish Since the contact 63 is grounded at65 and the contact 64 is connected by a lead 68 to one terminal of anelectromagnet 67, the other terminal being connected by a lead 68 to thelead 31fron the 'generator 32, engagement of the contacts 63 and 64energizes the magnet 67, .thereby causing attraction of the armature 70pivoted on the same spindle 37 which forms the pivot for the armaturemember 35. The armature member 70 provides a lever arm 71 !orcooperation with the leit hand table dog 8 in the following manner saidtable dog 8, as shown in Fig. 1, is pivoted to its carrying block 42,and normally restsby gravity against a pin, thereby to maintain its freeend in position to engage and move the reversing member 9 at the end ofthe right hand normal working stroke of the table 1. When the magnet 67,in response to the grinding of the workpiece to the exact desired size,is energized, the lever arm 71 is raised into the path of dog 8, and thelatter on the right hand movement of table 1, by reason of itspivotalmounting is free to ride on the upper surface of said lever arm;thus the striking end of said dog 8 is carried clear of the reversingmember 9, and'the table 1 continues its movement to the right, carryingthe grinding wheel 5 out of the workpiece and well past the theninoperative dressing device 38, said table ultimately carrying thegrinding wheel 5 into the position illustrated in Fig. 1, and therebeing brought to a full 'stop by any suitable means, such for example,as shown in the above cited Heald and Guild Patent No. 1,5 82,468. Thuswith the coming to size of a given workpiece 6, the mechanismautomatically secures the complete cessa- 'tion of the grindingoperation, and the full longitudinal separation of the grinding wheelfrom the workpiece, permitting access to said workpie'ce for its removalfrom the machine, and the insertion in said machine of a new ungroundworkpiece while the grinding wheel 5 is entirely out of the way.

On the return to working position, from the fullwithdrawal positionshown in Fig. 1, an arm 72,

pivoted at 47 and hanging by gravity in the position shown in Fig. 3,strikes an arm 73 of the movable switch member, thereby, rocking saidswitch member so that its Connector 30 is returned to the position shownin Fig. 3, in readiness for the energization, at the proper time in thegrinding of the next workpiece, of the electromagnet 25 whichinaugurates, as above described, the wheel dressing operation. As shownin Fig. 3,

offset !rom one another, as are also the corresponding striking arms46'and 72 respectively of the table 1. During the withdrawal tor thedressing operation, the arm 72 -is not carriedfar enough to engage thearm 73 so that the movable member is not reversed until the wheel ismoved into position for grinding a new workpiece. I

From a c'onsideration of Fig.'3, it will be seen that as the movableswitch member is returned to engagement with the plate 27, on return ofthe table to operative position relative to a new workpiece, the circuitthrough the electromagnet 52 is broken by separation of plate 30 andplate 50, and the pawl 17 is thereby permitted to return to operativeengagement with the ratchet 18 so that," during a subsequent grindingoperation, the cross-feed movement may again be obtained in the mannerabove set forth until the-subsequent dressing operation.

Referring to the modification shown in' the diagram of Fig. 4, theconnection of the Operating parts is intended' for use in a machine ofthe type shown in the above cited Guild patent, in which constructionthe movements of the reciprocatin table are procured by movements of themechanism which obtains the cross-feed. For the purposes of the presentinvention, it is sufilcient to note that the grinding wheel is withdrawnfrom the workpiece for a dressing operation before the grinding iscompleted and is again withdrawn, after the final cut, to rest positionin order to permit insertion of anunground workpiece, by mechanismmounted on and cooperating with the cross-feed mechanism, the operationof which will be described with relation to the machineinstrumentalities of Fig. 1. The present modification contemplates thecessation of the crossfeed movement a predetermined time prior to theseparation of the wheel and lwork as will be pointed out. An annular camand ratchet ring is disposed about and rotates with the hub of a handwheel of the cross-feed mechanism corresponding to the handjwheel 19,above mentioned, and is actuated in a similar manner by a pawl andratchet mechanism, the pawl being indicated in this figure at 81. Thecam ring 80 carries a cam projection 82 which, in the clockwise rotationof the hand wheel and ratchet during the cross-feed movement of thegrinding wheel, engages successively with two adjustable screws 83 and84, engagement with screw 83 causing withdrawal of the wheel for thedressing operation and engagement with the screw 84 causing withdrawalof the wheel to rest position after the final grinding operation. Thescrew 83 is carried by a. pivotal member 85 and the rocking of thatmember, under the influence of the cam projection 82 causes engagementof two electrical contacts 86 and 8'7. Similar movement of the screw 84which is carried -by a pivotal member 88, causes the engagement ofelectrical contacts and 91; engagement of the first contacts 86 and 87closes a circuit which causes the wheel dressing instrumentalities ofthe machine to be brought into operation, while engagement of thecontacts 90 and 91 causes longitudinal separation of the grinding wheel5 from the workpiece 6, the ,former being moved to its extreme righthand position.

When the terminals or contacts 86 and 8'7 make r contact, an electricalcircuit is iormed which causes the table 1 to have an amplified stroketo the right, in order to withdraw the grinding wheel 5 from the work,and simultaneously causes a wheel dresslng member or diamond 38 to moveinto the amplified path of said grinding wheel, thereby to true theperiphery of the letter as lt passes the point of said diamond. As shownby the wiring diagram, electrical current may be supplied by a directcurrent generator 92 driven continuously by any suitable means, notshown, !rom the same source of power that is used for 'the rotation ofthe grinding wheel or the work spindle. One terminal of this generato'r92 is connected to a ground 93 by a lead 94, the latter carrying a,switch 95, normally in closed position, by which the electrical controlthrough the machine may be disconnected; the other terminal of thegenerator is connected to a supply lead 96, the latter being connectedby a lead 97 to an oscillatory plate 98 of a switch which is ,mounted onthe front of the machine. In the normal position of the oscillatoryplate 98, it is in contact with a plate 100* which is connected by alead 101 to one terminal of an electromagnet 102; the other terminal ofsaid electromagnet is connected by a lead 103 to the terminal 87. Theterminal'sfi is connected by a lead 104 to a grouncl 105. When the cam82 engages and lifts the screw 83, the' terminals-86 and 87 are broughttogether closing the circuit through the electromagnet 102 andenergizing the magnet, thereby causing attraction of an'armature member106 and the consequent elevation of its attached lever arm 107, theseparts being pivoted at 108 on the front of the iframe. such movement ofthe lever arm 107, responsive to the engagement of cam 82 and screw 83,operates in the manner of the above described lever arm 36 automaticallyto interrupt the grinding operation on the workpiece for the dressingand truing of the grinding wheel in advance of the final and finishingouts taken by said wheel to bring the workpiece to the desired size; adownward extension 110 of the lever arm 107 serving to actuate thedressng device in the manner of the downward extension 41 abovementioned.

On the amplied right hand d'essing stroke above pointed out theoscillatory plate ,is rocked out of engagementwith the plate 100,thereby breaking the circuit through the electromagnet 102 andpreventing a repetition of the dressing stroke, the oscillatory platebeing actuated by an arm 111, pivotally mounted at 112 on a portion ofthe reciprocatory table, in the manner of arm 46, said arm 111 engagingan arm 113 on plate 98 in line therewith.

Following this single extended movement of the table, the wheel is againreturned to the work in the manner disclosed in the above identifiedGuild patent for completion of the grinding operation. 'This continuedgrinding operation involves a further rotation of the cam 82 in aclockwise direction' eventually bringing the cam be brought together,contact of these terminals causing the table and the grinding wheelmounted thereon to be withdrawn from engagement with the work apredetermined time subsequent to the engagement of Contacts and 91 inthe following manner:-The terminal 90 is connected by a lead 114 to theground 105 and the terminal 91 is connected by a lead 115 to a solenoidcoil 116, the opposite end of said coil being connected by a lead 117 tothe supply lead 96 from the generator. Upon the energization 'of thesolenoid 116 by contact of terminals 90 and 91, a switch member 118 isattractedby the solenoid and provides an electrical connection betweenterminals 120 and 121. Terminal 120 is grounded at 122 and terminal 121is connected by a lead 123 to one termnal or a t me relay motor 124, theother terminal of said motor 124 being connected through a lead 125 andthe arm 126 of a switch 127 to a switch terminal 128, the latterterminal being connected by a supply lead 130 to the lead 96. The otherarm 131 of the switch 127 is connected by a lead 132 to one terminal ofan electromagnet 133, the other terminal of said magnet being connectedto the supply lead 96. When the switch 118 closes the circuit betweenterminals 120 and 121, the timeirelay motor 124 is put in operation sothat a predetermined time after engagement of contacts 90 and 91, theswitch 127 126 and terminal 128 and closing a circuit through the arm'131 to the electromagnet 133, a terminal 134 for the switch arm 131being grounded at- 135 to complete this circuit. Energization of theelectromagnet 133 causes attraction of the arma ture member 136 and theconsequent elevation of its attached lever arm 137, these parts beingpivoted on the shaft 108 which also forms the pivotal support for thelever 107. Upward movement of the arm 137' acts in the manner of the arm71 to separate the wheel and the workpiece just as the workpiece reachesthe exact desired size. t

When the cam 82 engages and actuates 'the screw 84, the cross-feedmovement is discontinued 'ciprocations imparted thereto by thereciprocating table movements without trans'mitting any movement to thehand wheel or the cross-feed mechanism actuated thereby.

It will thus be apparent that the cross-feed movement of the grindingwheel is discontinued at approxmately the same time that the screw 84 isactuated and, since the actuation of the screw 84 closes the circuit bywhich the wheel is separated from the work, that the separation willoccur at a predetermined time following'the closing of the said circuitdepending upon the time interval as adjustably established by thesetting of time relay motor.

The separation of wheel and workpiece by the lever 137 causes the table1 to be carried to its extreme right hand position to permit insertionof an unground workpiece into the workholding i chuck. Upon subsequ'entreturn of the wheel to Operating position for grinding the newworkpiece, said return being effected by movement of the table 1, an arm139, pivotally mounted on the support 112 for arm 111, engages an arm140 on the plate 98, and rocks 'said plate into nonnal position inengagement with plate 100 to permit during the succeeding grindingoperation, the energization of magnet 102 for withdrawal 'of the tablefor a dressing operation on the wheel, as above pointed out.

The Construction of the embodiment shown in Fig. 3 is not limited to theConstruction shown since, from a consideration of Fig. 4, it will bereadily apparent that a time relay motor or other time control devicemay be readily inserted in the circuit which controls the electromagnetfor separating the pawl and ratchet, with the result that the cross-feedfor the grinding wheel may be discontinued in any 'precletermined timerelation to' the movement either of the rough gauge which actuates thecontacts 20 and 21 or the finish gauge which actuates the terminals 63and 64.

I claim,

1. In a grinding machine, a grinding wheel having an operative positioninengagement with a workpiece, and an inoperative position axiallyspaced from the workpiece,means to procure a cross-feed movement betweensaid` wheel and a workpiece, means to procure axial withdrawal of saidwheel to inoperative position, and electrically actuated means toprocure cessation of said cross-feed movement prior to said withdrawal.

2. In a grinding machine, a grinding wheel, a cross-feed mechanism toprocure a cross-feed movement between said wheel and a workpiece,means'actuated by said cross-feed mechanism to procure a withdrawalmovement between said wheel and workpiece, and means to procurecessatio'n of said cross-feed mechanism prior to said withdrawalmovement, said means to procure the withdrawal movement including acircuit actuated by a time relay motor.

3. In a grinding machine, a grinding wheel, means to procure across-feed movement relative to a workpiece, means to procure anextended movement oi said wheel relative to the workpiece prior tocompletion of the grinding operation and subsequent return of the wheeland ,workpiece to operative position, and means responsive to saidextended movement to procure cessation of said'cross-feed movement whenthe wheel again 'engages the workpiece.

4. In a grinding machine, a grinding wheel, means to' procure across-feed. movement of said wheel relative to a workpiece, a gaugeadapted to have -an extended movement when the workpiece is ground to apredetermined size prior to the completion of the grinding operation,means actuated by the extended movement of said gauge to procurecessatlon of said crossfeed movement, and means subsequently operativeto procure withdrawal of the wheel from the workpiece.

5. In a grinding machine, a grinding wheel.

having an operative position in engagement with a workpiece and aninoperative position axially spaced from said workpiece, mechanism toprocure a cross-feed movement between said wheel and work, meansactuated by said mechanism to procure axial separation of said wheel andwork to inoperative position, and means to procure cessation of thecross-feed movement at a'. predetermined time interval prior to saidseparation, said time interval being determined by a time relaymechanism.

6. In a grinding machine, a grinding wheel having a traversing movementrelative to a workpiece, mechanism responsive to said traversingmovement to procure a cross-feed movement between said wheel andworkpiece, mechanism to,

procure withdrawal of'said wheel from the workpiece before completion ofthe grinding operation, means responsive to said withdrawal movement toprocure cessation of the cross-feed movement; means to return said wheelto the work', and further mechanism to procure separation of said wheeland work when the workpiece is ground to size. A

7. In a grinding machine, a grinding wheel having a traversing movementin operative relation to a workpiece, mechanism responsive to saidtraversing movement to procure a crossfeed movement between said wheeland workpiece including a ratchet wheel actuated by a pawl, a gauge,mechanism responsive to said gauge to procure an extended movement ofsaid wheel relative to the workpiece to withdraw said wheel' from theworkpiece when the workpiece is ground to a predetermined size, magneticmeans actuated by said extended movement to withdraw said pawl from saidratchet wheel, 'mechanism subsequently to return said wheel to operativepositraversing movement to' procure a cross-feed movement between saidwheel and workpiece including a pawl for actuating a ratchet wheel,withdrawal meansresponsive to said cross-feed movement to procure awithdrawal movement i of the wheel from the work, other. means reisponsive to said cross-feed movement to separate said pawl from saidratchet when said withdrawal means are' actuated, said withdrawal meansincluding a circuit having a time relay therein to procure saidwithdrawal movement a predetermined time subsequent' to the cessation ofthe 'cross-feed movement.

9. In a grinding machine, a grinding member and a workholding member, atable on which one of said members is mounted, said table having anoperative position with the grinding member in engagement with aworkpiece in said workholding member, and an inoperative position withsaid grinding member axially spaced from the workpiece, means to procurea cross-feed movement between said grinding member and said workpiece,automatic means to procure axial separation of said grinding member andsaid workpiece by movement of said table to inoperative position, andelectrically actuated means to procure cessatlon of the cross-feedmovement prior to axial separation of the grinding member and theworkpiece. i 10. In a grinding machine, a grinding wheel. means toprocure a cross-feed movement of the wheel relative to a workpiece, agauge adapted to engage the ground surface of the workpiece when thelatter is` ground to a predetermined size to procure separation of thewheel and workpiece, said wheel and workpiece being subsequentlyautomatically returned' to operative position, and means actuated bysaid separation to procure cessation of said cross-feed movement.

11. In a grinding machine, a grinding wheel and a workpiece, a table onwhich one of said members is mounted, means to procure a crossfeedmovement between said wheel and workpiece, means to procure movement ofthe table for a separation between said wheel and workpiece. beforecompletion of the grinding operation, means responsive to saidseparation to procure cessation of the cross-feed movement, means toreturn said wheel and work to operative relation, and further mechanismto procure separation of said wheel and work when the latter is groundto size.

`12. In a grinding machine, a grinding wheel, a.

mechanism-to procure a cross-feed movement between said wheel and aworkpiece, mechanism to procure withdrawal of said wheel from theworkpiece before completion of the grinding operation,'

means responsive to said withdrawal to procure cessation of thecross-feed movement, means to return said wheel to the work and furthermechanism to procure separation of said wheel and work when the latteris gro'md to size.

13. In a grinding machine, a grinding wheel, a cross-feed mechanism forprocuring a crossfeed movement between said wheel and a workpiece, atime relay motor, means for procuring cessation of the cross-feedmovement and for setbetween said grinding member and said work-` piece,automatic means to procure axial separation of said grindng member andsaid workpiece by movement of said. table to inoperative position, andelectrically actuated means governed by the size of the workpiece toprocure cessation of the cross-feed movement prior to' axial-separationof the grinding member and the workpiece. l 15. In a grinding machine, agrincling member and a workholding member, a table on which,

one of said members is mounted, said table having an operative positionwith the grinding member in engagement With a workpiece in saidworkholding member and an inoperative position with said grindingmember` axially spaced from the workpiece, means to procure a'cross-feed movement between said grinding member and said workpiece,automatic means to procure axial separation of said grinding member andsaid workpiece by movement of said table to inoperative position, andelectrically actuated means governed by the extent of the cross-feedmovement to procure cessation of the cross-feed movement prior to axialseparation of the grinding member and the workpiece.

HAROLD L. BLOOD.

